Results

The list of cases has been analysed based on the information listed above. The results are shown in the same order as above.

Of the 291 cases, 25% (73 cases) of these led to an actual chemical release, and only 16% (47 cases) led to loss of packaged goods1. Fortunately, the majority of the incidents did not lead to a release of chemicals, or packages containing chemicals, into the marine environment.

Ship types

In figure 53 the cases are divided by ship type. Most of the recorded accidents involved general cargo ships. Most chemical releases are the result of distress situations with chemical tankers. According to this data, distress situations with barges more often lead to a chemical release. A distress situation concerning a barge has less chance of ending up in the maritime HNS spills databases if no actual spill occurs.

When looking at incidents in the last 30 years more closely (Figure 54). An increase towards 1995 is seen and a general decrease afterwards, with a peek in 2001. After 2006, a growing trend is observed again. This information is hard to interpret, because this graph shows all recorded incidents; great catastrophes, and distress situations that did not lead to spills.

Locations of spills

Analysis of the locations that the incidents occurred (Figure 56) shows that most incidents occur at open sea. However, taking into account that on average a ship spends a lot more time at sea than in harbour, relatively high number of incidents occurred in harbour area.

Cause for distress

Figure 57 shows the main cause of distress for each of the cases, with fire/explosion being the distress situation most represented in the list. However, only a small fraction of these cases led to a release of HNS. (58 cases, of which 8 led to a spill). Again, most cases that led to a spill are due to collision (18 cases of chemical release after a collision), while groundings and fire/explosion also represent (106 cases of which 21 led to a spill.

A fact worth noting: in the list of incidents, 59 incidents (20%) are marked ‘distress because of cargo’. This means that the HNS cargo either caused the distress situation or worsened it.

Figure 58 shows all these relevant cases, divided by cargo type, most of which (52%) involve bulk goods. A distress situation with a ship carrying bulk goods is more likely to lead to a release of substances than a distress situation with a ship carrying packaged goods.

Thirty-six percent of the distress situations involving bulk goods led to a release, in comparison to fifteen percent of the distress situations with packaged goods.

It is believed that the loss of packaged goods is seriously underestimated in this list. Not every case of lost packaged goods is listed in the HNS incidents statistics. For now, these cases were left in the analysis because this is still an important scenario to be aware of.

Chemical release of HNS goods

The spill causes for the 73 cases that actually led to a release of HNS substances are shown in Figure 59. Distinction was made between packaged goods and bulk goods.

It is clear that a leak is the most common reason for substances to be released into the environment (36 %). Also sinking of ships accounts for a substantial percentage of the number of spills (25 %).

Loss of packaged goods

The list of cases of lost packaged goods is probably nowhere near complete. The cases reported are cases in which a serious distress situation caused the loss of packages, or cases that led to loss of huge amounts of packages.

Listing every single lost container would be an impossible task and probably not very relevant. These kinds of situations happen on a daily basis, concerning containers with a wide variety of cargo from consumer products to industrial chemicals to personal belongings.

Four different categories of losing packages were distinguished; the following table shows how the 46 cases from our list are divided amongst those categories.

Table 15 Reasons for loss of packages

A	General (no specific reason)	11 %
B	Loss overboard	59 %
C	Deliberate discharge	2 %
D	Sunken ship	28 %

It appears that the most common cause of package loss is bad weather. Thus Figure 60 as 24% of the cases being due to this cause, while 7 of the cases (11%) occurred for no stated reason and 7% are attributed to collisions.

Substances involved Types of substances

Table 16 divides the cases of chemical releases per category of substance. The different cargo categories are limited; this is because HNS substances are not found in a lot of cargo categories. For instance consumer items are not very likely to contain large amounts of HNS substances. As expected, most HNS goods spilled were for industrial purposes, however food and agricultural products together account for 23% of the spills.

Table 16 substance categories of the released substances

cargo category	No. of cases	Avg. Gravity scale value	Avg. Release amount (Tonnes)
agricultural	7,00	4,79	1560
food	10,00	6,62	3439
industry	53,00	5,33	3636
unknown	1,00	u	u
Total	73	5,41	3403

This does comply with the findings analysing the Top 100 of most transported chemicals in bulk (paragraph 2.5); the food product palm oil is the biggest contributor to the list with 19% of the amount transported.

The recorded food spills have a higher gravity scale value than the recorded spills of goods for industrial purposes. However statistical Analysis with ANOVA proves the difference between both populations is not significant.

Substances

Of 227 of the 288 cases, the exact substance involved can be found. The other 61 cases comprise mixed substances, substances not mentioned by name or unknown substances.

102 different substances are distinguished, most of which only occur in the list once. 35 of the substances are involved in more than one incident.

Comparison of the substances with the top 100

The substances involved in the distress situations in the case histories list were compared to the substances listed in the Top 100 most frequently transported harmful chemicals in the European ports and coasts (paragraph 2.5);

When looking at the complete list, the percentage of substances listed in the top 100 is relatively low. This is due to the large amount of mixed and unknown substances.

Because the top 100 actually only deals with substances carried in bulk, the cases comprising bulk goods were isolated from the list.

In top 100	79	53 %
Not on top 100	50	33 %
Unknown or mixed substances	21	14 %
Total	150	100 %

Of the 54 cases of bulk goods being released into the environment, 41 cases (76%) concern goods that are listed in the top 100.

Listing the cases per substance doesn’t result in a very informative graph. However if the numbers of accidents are summed per 5 substances, there appears to be a trend in number of accidents and ranking of the substances in the top 100. In general, more accidents happened with substances ranked high in the top 100.

There are two deviations of the expected trend:

1. A peek of accidents with substances ranking from 71 to 75.
2. A peek of accidents with substances ranking from 11 to 15.

Main contributor to the category of substances ranking between 71 and 75 are 5 accidents with potassium hydroxide (potash) are listed.

The peek in rankings 11 to 15 is due to 8 accidents with sulphuric acid.

No specific reason for these deviations could be found, however such deviations are not unlikely in a sample size this small (n=79).

Figure 63 shows the behaviour classification of those substances that were actually spilled. Most substances behave as dissolvers or evaporators/gases.

Response options

In a very simplified manner, appropriate response options were added to the database;

First of all, logically most of the cases, comprised a ship in a distress situation. It is very important for responders and decision makers to be able to cope with this situation.

In case of a release, as shown in Figure 63, the substances that were actually released to the environment are mostly Evaporators/gasses and Dissolvers. These substances are hard to respond to, and in most cases only monitoring is a viable response option.

Then there are the cases in which no release had taken place. In some of them, the distress situation was controlled and the ship could sail on to either the nearest port or its original destination, however 176 cases (theoretically) required a salvage job.

Recovery of a ship carrying HNS:
	Sunken	83
	Grounded	46
Recovery of packaged goods:
	From a (sunken) vessel	13
	From the marine environment	34
		176

Conclusions

Based on the gathered cases, the following conclusions can be made:

Most incidents occurred at open sea, however compared to the time spent in harbour, a relatively large portion of incidents occurred in harbour area.

Collisions, groundings and fire/explosions are the most common causes of distress leading to a substance to be released into the marine environment.

The most occurring cause of spill for these cases was a leak or sinking of the ship.

More cases of distress situations with bulk goods were recorded than cases of packaged goods. Proportionally, distress situations with substances in bulk, more often lead to a release of the substance into the marine environment.

Most of the HNS substances released into the marine environment were intended for industrial use. However agricultural and food products also accounted for a substantial portion of the cases.

Most accidents with bulk goods happened with substances listed in the Top 100 most frequently transported harmful chemicals in the European ports and coasts (paragraph 2.5). As expected, more accidents happened with substances ranked high in the list.

From the recorded cases of packaged goods being lost into the marine environment, loss overboard is the most common reason and storm is the most common distress situation.

Recommendations

In future analysis of this data, a ranking of seriousness should be added. The given analysis is based on all cases in which case minor incidents and major catastrophes are treated the same.

The Koops Gravity Scale provides a useful tool for ranking the incidents.